I'm going to post something here that may or may not be germane to only the OP: quit trusting data from Zwift. Zwift is a game - and the insidious part of it is that it incorporates cycling data, but then does 'other stuff' to it to give users an emotional experience that leads to further use and renewal. In other words, it's a blend of science and Barnum-esque showmanship that plays with your perceptions.
You have improvement on the trainer but haven't gone outside to climb again yet? Perhaps time to do so?
Or, if you're wanting to be a 'trainer only' rider, then at least get a better source of data than Zwift, for crying out loud.
Clmbing is a skill, one you can work on. Please don't take any physiological advice with potential medical ramifications from self-appointed 'experts' on an online forum. They can tell you their experiences, and that's about it.
It seems that you are ready for a training plan. If so, please take an approach that is more serious than getting data from Zwift and physiological advice from internet strangers.